I am adding panels to the tabbedpanel. To successfully complete this operation both the tabbedpanel and panel to added must be first created and available in formspider designer.

My question is how formspider panel disign screen add undefined number of panels at runtime? Have you created all the these panels in advance or is there a method to create these panels dynamically and add it to the tabbedpanel at runtime? I am asking as I also need to have a similar functionality in my development.

The Formspider design screen is not a tabbedPanel, instead, it's the Formspider editor component. Therefore, it's the editor component who manages the creation of new XML editor instances when new editor tabs are added.

Unfortunately, it's not currently possible to create panels at runtime.